In the world of professional sports, everyone who plays at the highest level is a near-superhuman athlete. To play a single minute -- hell, to even get a roster spot -- on a team in the NFL, NBA, NHL, or almost any league, you need to be in the 99th percentile of athletes in your position. Yes, there are exceptions , but this point still mostly holds. So what separates the good athletes from the truly great ones? What’s the difference between the “just fine” players (the Kirk Cousinses, Jimmy Garoppolos, and Ryan Tannehills of the world) and, say, Joe Montana? Largely, the answer lies in their mentality. No, your mental fortitude isn’t absolutely everything -- even if I had the most killer-instinct mindset imaginable, I’d wager Julio Jones would still have a better NFL career than me. However, between those already in the 99th percentile, how you study, prepare, and visualize success is often the deciding factor between having a solid career and having a Hall-of-Fame one. Perhaps mos...